Why birds don't get electrocuted on electric wires ?

Most common doubt that arises when we see the birds freely sitting on power lines is “Why birds don't get electrocuted on power lines??”

For this question, we might have heard plenty of answers like “Bird’s feet are of a special kind which is not good conductors of electricity “in various versions but it’s just a myth. The reason why birds won’t get electrocuted on the power line is;

For a current to flow through any path it should meet two conditions

1. Closed-loop circuit – Electric current is defined as the flow of electrons. These electrons originate from source (like battery or generator) move through the power lines to our equipment and travel all the way back into the earth/neutral of the source to complete a circuit. In case if this circuit is open somewhere then no current flows. An electric switch is a perfect explanation for this where when you switch off it simply opens the circuit and stops current to flow through it.

2. Potential difference - Another factor which decides the direction of flow of current is (electric) potential (voltage difference). Always current flows from a higher potential to a lower potential. Suppose two beakers of water at different levels are connected with a pipe, then the water flows from the beaker with more water into the one which has less water. The same happens in the case of electric current also. Since the phase wire or live wire has some voltage and ground wire has zero voltage, the difference of voltage between these two will gives energy for electrons to flow through the circuit.

Now let’s see what happens in case of birds sitting on live wires based on the above principles of electric current. When a bird is sitting on a single wire, its two feet are at the same electrical potential, so the said electrons in the wires have no voltage difference to travel through the bird’s body. No moving electrons means zero electric current. Hence the bird is safe, for the moment, but if that bird stretches out its wing or a leg and touches a second wire, especially the one with a different electrical potential, it will immediately create a voltage difference between two legs of a bird and open a path for the electrons to rush right through the bird’s body.

Sometimes we will be noticing a few birds lying dead near power lines. If the above case is right how did they die or how those birds got electrocuted?

The answer to this is the current pole. This current pole which is buried deep in the ground supports the electric wires, which when gets touched by a bird already sitting on the live wire will create a closed-loop path as well as potential difference (Live wire with some voltage and earth with zero voltage) This is the shock that people encounter if they touch live wires — since we are almost always in contact with the ground. Our bodies will behave as an  excellent conductors of electricity and the electrical current will effectively use them to complete a closed path to flow from high potential (the wire) to low potential (the ground) and ZAP !!! That’s the reason why electrical safety shoes will be used by the people working on the live power lines which avoid human body contact with the ground.